1. Depending what game u are wanting to make depends how you go about making it. if its steam games eazy you put the steam id into the steam part in the config that will download it.
as for windows to linux it can be done you just need to tweak with some settings ie anything that use windows commands will have to be changed.
you can make then export them.
All you need is the xml unless you have added mods.
Take a look at some of the linux game configs that come with tcadmin that will help you on your way if there is anything els you need just post